Question

Consider the following two acids: pKa1 = 2.98; pKa2 = 13.40

HO2CCH2CH2CH2CH2CO2H Adipic acid
pKa1 = 4.41; pKa2 = 5.28
In two separate experiments, the pH was measured during the titration of 5.00 mmol of each acid with 0.200 M NaOH. Each experiment showed only one stoichiometric point when the data were plotted. In one experiment the stoichiometric point was at 25.00 mL added NaOH, and in the other experiment the stoichiometric point was at 50.00 mL NaOH. Explain these results. (See Exercise 83)